1. Field of the Invention
This invention relates to a method of operating an adsorption refrigerator which permits an enhancement of the refrigeration efficiency. More particularly, the invention is designed to provide a method of operating an adsorption refrigerator in which two adsorption columns are directly connected through a pipeline equipped with a valve.
2. Statement of Related Art
Of adsorption refrigerators which avail themselves of adsorption and desorption actions of a solid adsorbent to and from a refrigerant to generate cold or to perform heat pump operation, such refrigerators that take advantage of low-grade heat sources, for example, warm water made available from solar collectors, etc. (e.g. warm water on the order of 85.degree. C.), or waste heat from works have many advantages that waste energy otherwise discarded can be harnessed effectively; and that they are each made up of a smaller number of mobile components such as pumps, which fact means more economical apparatus cost, and have a smaller operation noise, as compared with compressor type refrigerators.
The adsorption refrigerators of this type, in general, comprise two sets of adsorption columns each sealed with a refrigerant and housing therein a solid adsorbent such as silica gel, zeolite, activated charcoal, activated alumina, etc. installed in parallel to each other, a condenser and an evaporator and are systematized so that a heat transfer medium for heating the adsorbent and cooling water may be supplied alternately to both adsorption columns to repeat alternately desorption and adsorption phases whereby refrigerating power output can be continuously obtained.
A problem with such prior art adsorption refrigerators is that shortly before one cycle of adsorption and desorption phases is changed over between the adsorption columns, the one adsorption column just having been at the desorption phase is full of refrigerant vapor driven off from the solid adsorbent, and, when changed over to an adsorption phase, is initially obliged to adsorb the remaining refrigerant vapor filled therein. As a consequence, at an initial stage when a new cycle of adsorption and desorption phases was started soon after the change-over, it was difficult to do its inherent work, namely to adsorb the refrigerant liquid in the evaporator to obtain a required refrigerating power. Thus the resulting refrigeration power output has been diminished.
The present inventors have already proposed and disclosed a more efficient operation method for such adsorption refrigeration system in order to further enhance its refrigeration power output (U.S. Pat. No. 4 594 856). According to this method, immediately before adsorption and desorption phases are changed over between two adsorption columns, residual heat such as warm water remaining within the desorption side column is transferred to the other adsorption column immediately before coming into a desorption phase thereby to preheat the solid adsorbent in the latter column, followed by change-over. This allows to utilize effectively the heat quantity of the system, but has also encountered the aforesaid problem.
Therefore, with a view toward solving the problem, this invention has been accomplished and has for an essential object to achieve an enhancement in refrigeration efficiency of an adsorption refrigerator as stated above in a procedure that, shortly before one cycle of adsorption and desorption phases is terminated, comprises shutting off paths for refrigerant and further advancing the respective adsorption and desorption phases between two adsorption columns thereby to utilize efficiently refrigerant vapor filled in the adsorption column and subsequently changing over to a next cycle of just opposite phases.
Another object of this invention is to provide a method of operating an adsorption refrigerator meeting both high refrigeration efficiency and a relatively simple manipulation procedure.